class_docstr: Treemap graph class
code: def _plot(self):
      total = sum(map(sum, map(lambda x: x.values, self.series)))
      if total == 0:
          return
  
      gw = self.width - self.margin_box.x
      gh = self.height - self.margin_box.y
  
      self.view.box.xmin = self.view.box.ymin = x = y = 0
      self.view.box.xmax = w = (total * gw / gh) ** 0.5
      self.view.box.ymax = h = total / w
      self.view.box.fix()
  
      self._binary_tree(self.series, total, x, y, w, h)
  
file_path: pygal/pygal/graph/treemap.py
imports: from pygal.adapters import none_to_zero, positive
  from pygal.graph.graph import Graph
  from pygal.util import alter, cut, decorate
label_desc: Use image node_id 5 for calling the Treemap obj's underlying member method code with example usage: obj._plot() without return types